The invention relates to the treatment of bone conditions in humans and other animals.
Several companies offer mechanical bone cement injection devices. These devices are similar to a household caulking gun. Typically, the injection device has a pistol-shaped body, which supports a cartridge containing bone cement. The cement is typically in two-parts and must be mixed in a mixer and transferred into the cartridge for injection.
Just after mixing, and prior to curing, the cement is in a flowing, viscous liquid state, similar to a syrup or watery pancake batter in consistency. The injection device has a ram, which is actuated by a manually movable trigger or screwing mechanism for pushing the viscous bone cement out the front of the cartridge through a suitable nozzle and into the interior of a bone targeted for treatment.
Once injected into the targeted bone, the cement undergoes a curing cycle of perhaps 6 to 8 minutes. While curing, the cement passes from a viscous liquid to a putty-like consistency and finally to a hard rigid block.
The invention provides, in its various aspects, greater control over the placement of cement and other flowable liquids into bone.
One aspect of the invention provides an injector nozzle assembly for injecting flowable materials into bone. The assembly comprises a tube body including an interior bore to carry a material flow. The tube body includes a dispensing end having an opening communicating with the bore to dispense the material flow. According to this aspect of the invention, the assembly includes a cutting element, which extends in the opening to normally permit passage of the material flow, but which severs the material flow in response to rotation of the tube body. The cutting element provides the means, carried as an integral part of the nozzle assembly, to provide a consistently clean break between an expelled bolus of material and material residing in the tube body.
Another aspect of the invention provides an injector nozzle assembly in which the dispensing end of the tube body includes a side wall having an opening to dispense the material flow. According to this aspect of the invention, rotation of the tube body severs the material flow at the side opening.
Another aspect of the invention provides an injector nozzle assembly having a tube body and a dispensing end, which is deflected from the axis of the tube body. The deflection of the dispensing end permits targeted introduction of flowable material into the middle region of treatment site, even when the access path does not align the tube body itself along the natural geometric axes of the treatment site.
In one embodiment, material in the tube body is biased to deflect the dispensing end toward a normally deflected position. The material can comprise, e.g., memory wire carried in the tube body, or a thermally set condition.
In one embodiment, a guide sheath holds the tube body for sliding movement between first and second positions. In the first position, the dispensing end is confined within the guide sheath and moves within the guide sheath in a generally straightened orientation. In the second position, the dispensing end is moved outside the guide sheath and assumes the deflected position. The guide sheath permits deployment of the normally deflected dispensing end into bone by percutaneous access.
In another embodiment, the tube body carries at least one steering wire to deflect the dispensing end. In this embodiment, the assembly can include a mechanism on the tube body coupled to the steering wire to move the steering wire, and thereby selectively deflect the dispensing end.
According to another aspect of the invention, the injector nozzle assembly includes a connector to releasably connect the tube body to a cement injecting tool. In this aspect of the invention, the connector includes a rotating fitting to permit rotation of the tube body relative to the connector. Upon connection to an injection tool, such as a cement gun, the rotating fitting allows the physician to rotate the injection nozzle assembly to control orientation and position in the treatment site, without rotating the injection tool itself. Combined with a cutting element or a side dispensing opening, as described above, the physician can rotate the tube body to cut loose an expelled bolus of material, without rotating the injection tool.
In one embodiment, at least one of the rotating fitting and tube body includes indicia by which rotation or orientation of the dispensing end can be gauged, without need to visualize the dispensing end within the bone.
Another aspect of the invention provides an injector nozzle assembly which includes at least one interior lumen adapted to communicate with a source cooling fluid to circulate cooling fluid while the dispensing end dispenses a flowable material which generates heat.
Another aspect of the invention provides methods for injecting flowable materials into bone using a selected one of the injector nozzle assemblies previously described.